package db

import (
	"context"
	"database/sql"
	"strings"
)

// ObjectHit 对象搜索结果条目。
type ObjectHit struct {
	Schema string `json:"schema"`
	Name   string `json:"name"`
	Type   string `json:"type"` // table | view
}

// SearchObjects 按关键词模糊搜索表/视图,最多返回 50 条。redis 返回空。
func SearchObjects(ctx context.Context, c ConnReq) ([]ObjectHit, error) {
	ctx = reqCtx(ctx)
	if isRedis(c.Driver) {
		return []ObjectHit{}, nil
	}
	var out []ObjectHit
	err := withDB(c, func(db *sql.DB) error {
		var err error
		switch {
		case isMySQLFamily(c.Driver):
			out, err = searchObjectsMySQL(ctx, db, c.Database, c.Keyword)
		case isPostgresFamily(c.Driver):
			out, err = searchObjectsPostgres(ctx, db, c.Keyword)
		case isMSSQL(c.Driver):
			out, err = searchObjectsMSSQL(ctx, db, c.Keyword)
		case driverKey(c.Driver) == "oracle":
			out, err = searchObjectsOracle(ctx, db, c.Database, c.User, c.Keyword)
		case driverKey(c.Driver) == "sqlite":
			out, err = searchObjectsSQLite(ctx, db, c.Keyword)
		default:
			err = unsupportedDriverErr(c)
		}
		return err
	})
	if err != nil {
		return nil, err
	}
	if out == nil {
		out = []ObjectHit{}
	}
	return out, nil
}

func likePattern(keyword string) string {
	return "%" + keyword + "%"
}

// hitType information_schema 的 table_type 含 VIEW 即为视图。
func hitType(tableType string) string {
	if strings.Contains(strings.ToUpper(tableType), "VIEW") {
		return "view"
	}
	return "table"
}

func searchObjectsMySQL(ctx context.Context, dbh *sql.DB, database, keyword string) ([]ObjectHit, error) {
	// database 为空时用当前库 DATABASE()
	q := `SELECT table_schema, table_name, table_type FROM information_schema.TABLES
		WHERE table_schema = DATABASE() AND table_name LIKE ? LIMIT 50`
	args := []interface{}{likePattern(keyword)}
	if strings.TrimSpace(database) != "" {
		q = `SELECT table_schema, table_name, table_type FROM information_schema.TABLES
			WHERE table_schema = ? AND table_name LIKE ? LIMIT 50`
		args = []interface{}{database, likePattern(keyword)}
	}
	return scanObjectHits(ctx, dbh, q, args, "mysql")
}

func searchObjectsPostgres(ctx context.Context, dbh *sql.DB, keyword string) ([]ObjectHit, error) {
	return scanObjectHits(ctx, dbh,
		`SELECT table_schema, table_name, table_type FROM information_schema.tables
			WHERE table_schema NOT IN ('pg_catalog','information_schema') AND table_name LIKE $1 LIMIT 50`,
		[]interface{}{likePattern(keyword)}, "pg")
}

func searchObjectsMSSQL(ctx context.Context, dbh *sql.DB, keyword string) ([]ObjectHit, error) {
	// MSSQL 无 LIMIT,用 TOP 50
	return scanObjectHits(ctx, dbh,
		`SELECT TOP 50 TABLE_SCHEMA, TABLE_NAME, TABLE_TYPE FROM information_schema.TABLES
			WHERE TABLE_NAME LIKE @p1`,
		[]interface{}{likePattern(keyword)}, "mssql")
}

func searchObjectsOracle(ctx context.Context, dbh *sql.DB, database, user, keyword string) ([]ObjectHit, error) {
	owner := strings.ToUpper(strings.TrimSpace(database))
	if owner == "" {
		owner = strings.ToUpper(strings.TrimSpace(user))
	}
	return scanObjectHits(ctx, dbh,
		`SELECT owner, table_name, 'table' FROM all_tables WHERE owner = :1 AND table_name LIKE :2
			UNION ALL
			SELECT owner, view_name, 'view' FROM all_views WHERE owner = :3 AND view_name LIKE :4
			FETCH FIRST 50 ROWS ONLY`,
		[]interface{}{owner, likePattern(keyword), owner, likePattern(keyword)}, "oracle")
}

func searchObjectsSQLite(ctx context.Context, dbh *sql.DB, keyword string) ([]ObjectHit, error) {
	return scanObjectHits(ctx, dbh,
		`SELECT '', name, type FROM sqlite_master WHERE name LIKE ? AND type IN ('table','view') LIMIT 50`,
		[]interface{}{likePattern(keyword)}, "sqlite")
}

func scanObjectHits(ctx context.Context, dbh *sql.DB, q string, args []interface{}, dialect string) ([]ObjectHit, error) {
	rows, err := dbh.QueryContext(ctx, q, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := []ObjectHit{}
	for rows.Next() {
		var schema, name, typ string
		if err := rows.Scan(&schema, &name, &typ); err != nil {
			return nil, err
		}
		t := "table"
		switch dialect {
		case "sqlite":
			t = typ // sqlite_master.type 直接是 table/view
		default:
			t = hitType(typ)
		}
		out = append(out, ObjectHit{Schema: schema, Name: name, Type: t})
	}
	return out, rows.Err()
}